The invention relates to a system and method of repeatedly observing the absorption of electro-magnetic radiation by a plurality of sample aliquots during a period of time. More particularly, this invention concerns the analyzing of a plurality of samples each of which may provide a single aliquot or plurality of aliquots which are subjected to chemical reactions with different reagents.
The term "aliquot" as employed herein is a noun meaning a portion of a sample. The term "auxiliary sample" is used herein to encompass control or standard samples, emergency-type samples, and similar fluids in distinction from a normally sequenced arrangement of patient samples. The system may measure kinetic reaction such as in enzyme analysis as well as end point or equilibrium conditions. Many chemical reactions requiring from a few seconds to several minutes may be initated substantially simultaneously and monitored to observe the progression of the reactions throughout a time period. The parameter measured is the absorbance of electromagnetic radiation of a particular wavelength or wavelengths by the analyte.
One disadvantage of prior art analyzing systems is the inability easily to handle an emergency situation as it arises without destroying the total sequence of operations of the system. In such systems the samples are laid out in a predetermined order to be tested, such as 1 through 50 with the identification and position of each of the samples being fixed. If during the sequencing of the samples and the tests run on the samples an emergency situation or stat test is desired, a position is robbed of its sample. The emergency situation or stat test is a sample which must be analyzed immediately and thus the programmed sequence of testing in progress must be interrupted. Each of these stat tests changes the programming of the tests and samples already in the programmed test sequence in the analyzer. Each change in the predetermined order or programming of the tests amd sample locations correctly must be entered and correlated so that the alteration of the sequencing is correctly noted in the system. This may result in the mismatching of a test and a sample resulting in an improper analysis related to a particular patient and all those following the mismatch in the sequence. It is extremely critical that a system accurately observe each sample reaction mixture being tested as will as have the flexibility to handle an emergency or stat situation should it arise during a sequence of testing without endangering the correct correlation of the test and samples already in the testing sequence.
A second problem encountered by the prior art devices is caused by dedicated reagent positions and typically a dedicated reagent dispensing mechanism for each position. In this case the array of cuvettes is segmented or divided into the number of positions required by the dedicated reagent positions. For example, 100 cuvette positions with 10 reagent positions results in samples from only 10 patients being tested without regard to the number of tests to be conducted on the sample from each patient. Patient No. 1 might require only one test, but all ten positions have to be alloted for that patient's sample in the device. Each of the nine empty positions may not be utilized so that the hundred position machine only is effective as a ten sample machine. If this problem is doubled by including ten second reagents, then the one hundred position machine would be divided in half again such that samples from only five patients could be analyzed at one time. This results in a great increase in elapsed time for a given throughput as well as a corresponding decrease in the efficiency of the operation.